Magnetic cilia, tiny artificial hairs powered by embedded magnetic particles, have long been used in applications like soft robotics, object transport, and liquid mixing. Now, researchers at North Carolina State University have developed reprogrammable magnetic cilia that can change their behavior at room temperature, opening new possibilities for adaptable, multi-purpose designs.

What Makes These Cilia Unique?

Traditional magnetic cilia use soft magnets that require an external magnetic field to function. However, the NC State team employed hard magnets, specifically neodymium-based microparticles, capable of generating their own magnetic field. This innovation allows the cilia to be programmed with precise magnetic polarization, dictating their motion when exposed to an external field.

Even more groundbreaking is the ability to reprogram the cilia. By erasing their initial magnetization and applying a new magnetic field, researchers can completely redefine how the cilia flex and move—like teaching a swimmer a new stroke.

How It Works

The process begins by embedding neodymium microparticles in a polymer slurry, aligning them with a powerful electromagnetic field. Once dried, the cilia behave uniformly under external magnetic influence. 

Reprogramming involves:

  • Freezing the Cilia: Fixing them in place with ice.
  • Resetting Magnetization: Using a damped, alternating magnetic field to erase the original magnetization.
  • Reprogramming: Applying a new magnetic field to set a different orientation.

This step-by-step process ensures precise control over the cilia’s behavior, including complex motions like snapping under rotating fields.

Future Applications

These reprogrammable magnetic cilia could revolutionize fields requiring adaptable soft actuators, such as robotics, biomedical devices, and environmental sensors. A computational model developed alongside this research can predict bending behaviors, helping design future iterations tailored to specific needs.

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